Afterburner shutoff valve



Jam 15, 1963 c. o. BRoDERs E-rAL 3,073,335

AFTERBURNER SHUTOFF VALVE 3' Sheets-Sheet 1 Filed May 5, 1959 ATTORNEYJan. 15, 1963 c. o. BRoDERs Erm. 3,073,335

AFTERBURNER sHUToFF VALVE Filed May 5, 1959 3' Sheets-Sheet 2 /NvENToRsCLAUDE o. @Roo/ERS TRE/vr H. HOLMES BV M 77 A T TORNEV Jap. l5, 1963 c.o. BRoDERs ErAL 3,073,335

AFTERBURNER SHUTOFF VALVE Filed May 5. 1959 A S'Sheets-Sheet 3 F/G. 4 /al/vvE/vrons CLAUDE o. noams TRE/vr H. HOLMES United states patent fkiff@ Patented Jian. l5, 1953 3,073,335 AFTERBURNER SHUTFF VALVE Claude0. Bruders, Simsbury, and Trent H. Holmes,

Rocky Hill, Conn., assignors to United Aircraft Corporation, EastHartford, Conn., a corporation of Delaware Filed May 5, 1959, Ser. No.811,197 9 Claims. (Cl. 137-340) This invention relates to shutoffvalves, more particularly to an improved shutoff valve for theafterburner fuel system of a gas turbine engine.

In the design of a shutoff Valve for an afterburner fuel system it is ofprimary importance that leakage through the valve gate be kept at anabsolute minimum. This tends to complicate the valve structure and theproblem is further intensified by the fact that environmental dimensionsrequire that the Valve size be kept as small as possible. Locating theValve gate at a necked-down section of the afterburner fuel line helpsto meet the size limitation. Still other important design considerationsare that the valve gate should have substantially friction-freeoperation without the imposition of unbalanced pressure loads thereonand that the valve gate elements should be maintained as cool aspossible.

IAn object of this invention, therefore, is to provide an improvedshutoff valve for an afterburner fuel system.

Another object of this invention is to provide an afterburner fuelsystem shutoff valve which has minimum leakage, substantiallyfriction-free gate operation and a pressure balanced gate seat.

Still another object of this invention is to provide an improvedafterburner fuel system shutolf valve of the sliding gate type, thevalve having a provision for the reverse flow of a cooling fluid and anarrangement of a ball track and hydraulically balanced seat to reducegate friction.

Other objects and advantages will lbe apparent from the followingspecification and-claims, and from the accompanying drawing whichillustrates an embodiment of the invention.

In the drawing:

FIG. l shows the complete fuel system for an afterburning gas turbineengine having therein the shutoff valve of our invention;

FIG. 2 is an enlarged section view of the shutoff valve of ourinvention;

FIG. 3 is a partial view looking into the shutoff valve from theupstream direction;

FIG. 4 is a View along lines 4 4 in FIG. 3;

FIG. 5 is a view along lines S-S in FIG. 3;

FIG. 6 is an enlargement of a portion of FIG. 5;

FIG. 7 is an enlargement of the check valve and gate seat portion ofFIG. 2; and

FIG. 8 is a view of the check valve and gate seal along lines 8 8 ofFIG. 3.

Referring to the drawing in details, in FIG. 1 fuel for the main andafterburner systems ,for gas turbine engine 10 is supplied from tank 12.Main fuel is withdrawn from the tank through conduit 14 by centrifugalpump 16 and discharged into passage 18 leading to gear pump 20. The gearpump substantially increases the pressure of the main fuel anddischarges it into conduit 22 leading to main fuel control 24. Fromhere, metered fuel passes through conduit 26 to ring manifold 28 to bedistributed to the various nozzles, not shown, within the burner sectionof engine 10.

Afterburner fuel is withdrawn from tank 12 through conduit 14 and branchconduit 30 by centrifugal pump 32 when afterburner shutoff valve 34 isopened. The pumped fuel is discharged into chamber 36 containingspring-loaded check valve 3S which will be opened by the pressure of thepumped fuel to admit the fuel to conduit dit and afterburner fuelcontrol 4Z. From here, metered afterburner fuel passes through conduit44, shutoff valve 46 of our invention, pressurizing and dump valve 48,and primary and secondary conduits Sil to ring manifold 51 within theafterburner of engine 10.

In order to cool various elements of the afterburner fuel system whenthe afterburner is not operating, engine fuel pump interstage fuel iscirculated through the elements to be cooled. Conduit 52 is connected topassage 18 between pumps 16 and 2@ and through it interstage fuel isdirected to pressurizing and dump valve i8 for cooling purposes. Thecooling fuel ow-s from the pressurizing and dump valve through conduit5d to shutoff valve 46. Within the shutoff valve the cooling fuel isintroduced into conduit 44, as will be explained below, and it thenllows back through the conduit, afterburner fuel control 42, and conduit56 to needle valve S8 which is integral with check valve 38. When theneedle valve is open, cooling fuel ilows through conduit 6d to conduit14 and the inlet to centrifugal pump 16.

Check Valve 38 and needle valve 5S function in a coordinated manner.When shutoff valve 34 is closed and the afterburner is not operating,spring 62 loads the check valve closed and the needle valve open, thuspermitting the circulation of cooling fuel flow through the afterburnerfuel system. However, when shutoff Valve 34 is opened and afterburnerfuel starts iiowing through the system, the pressure of the fuel inchamber 36 acting on check valve 38 will overcome the loading of spring62 to open the check valve and close needle valve 58. Of course, coolingflow through the afterburner fuel system elements is not needed when theafterburner is operating and the closing of the needle valve preventsafterburner fuel from being recirculated through conduit 60 back toconduit 14.

FIG. 2 shows the details of shutoi valve 46. Conduit 44 assumes theshape of venturi 6d within the valve and sliding gate 66 is located atthe throat of the venturi for controlling fuel ow to the engineafterburner. The sliding gate is of ilat form and it is connected byarticulated joint 6d, FIG. 3, to piston 7u which slides within sleeve72. The sleeve is integral with base housing 7d.

Recess 76 is formed in one end of piston 7i) for receiving stem 7S, partof the structure for transmitting a spring loading to'gate 66. Ball Silis formed on the end of stem '78 and lits within a socket in recess 76.The remainder of the load transmitting structure includes guide 82 andspring S4 which is mounted between iiange 86 on one end of the guide andabutment Sti within cap 9i?. The spring will act through flange 86,guide 32, stem 78, ball 80, and piston 7@ to maintain sliding gate 66 ina closed position in the absence of a dominating opposite load on thegate. The ball and socket connection compensates for any otf-squarenesserror in the spring and the force transmission through the center of thepiston tends to prevent rocking and tendency of the piston to bind whensliding in sleeve 72.

When fuel is admitted to the afterburner system, flow beyond gate 66 tothe afterburner initially is prevented by the gate. However, the fuel inconduit d4 flows through opening 92. defined between the wall of venturi64 and the gate intochamber 94 to the left of the venturi as well asinto chamber 96 to the right of the venturi. The pressure of the fluidacts to the left upon an effective area equal to that of a section ofpiston 7u and as the pressure of the fuel increases, the leftward forceon the piston becomes sufficiently great to overcome the loading to theright on the piston and move the gate in an opening direction. Fuel thenwill flow to the afterburner, variation of the gate position regulatingthe pressure upstream of the valve to at least a minmum differentialabove the reference pressure in chamber within cap Sil. When the Ilow offuel through the afterburner system is cut olf, the leftward force onthe piston will be reduced so that the rightward forces on the pistoncan close the gate.

Fuel from pump interstage is admitted to chamber 9-3 through conduit 54and acts together with spring to load piston '78 to the right. One ormore tubes 1% connect the interior of chamber to annular chamber 1d?.surrounding venturi 6dimmediately downstream of the gate. When theafterburner system is flowing fuel, cooling fuel is dead-ended inannular chamber lil?. by valve 1M, HG. 7, but when the afterburnersystem is inactive cooling flow passes through the valve and intoconduit 44 to circulate through the system back to the inlet for pump16.

Valve 104 is spring-loaded against seat 106 by spring 103. Whenafterburner fuel is admitted to conduit dit, the fuel flows throughopening 92 and hole 11G in piston 7G to chamber 1l?. to act incombination with spring ldd and position valve ltll against seat 106.When afterburner fuel ilow is stopped, the pressure of the cooling fuelin annular chamber 162 will overcome the load of spring 19S and open thevalve. In its open position valve 164 is positioned against retainer 11dwhich is provided with a plurality of indentations 116 to permit theilow of cooling fuel past the valve and retainer. The cooling fuel owsthrough hole 1153 and enters conduit d4 through opening 92. The coolingflow then is circulated through needle valve S3 back to the inlet forpump 16 as has been described above,

Sliding gate 66 is provided along its vertical edges with ball bearingsso that movement of the gate can be accomplished with a minimum offriction. One of the ball bearing units is shown at 11S in FIG. 3, andin the end view of FIG. 4 the arrangement of balls 12) and oval-shapedtrack 122 can be seen. As shown in FIGS. and 6, the edges of gate 66 aremachined away leaving projections 12.4 which dene the inner race fortrack 122. Oval-shaped ball retainer 126 is secured to gate 66 by screws12S, the retainer having lip 130 (FIG. 6) formed about its periphery toretain balls 126 in their track. Two sizes of balls are used, the largerdiameter balls being the load carrying balls and the smaller diameterballs acting as spacers to prevent climbing of the load carrying balls.The difference in diameter between the two sizes is in the order of onlya few thousandths of an inch.

When gate 66 is being moved, the pressure of the afterburner fuel inconduit 44 loads the gate in the downstream direction. At this timeballs 12) roll along track 13?. on the downstream side of the gate. Whenthe loading on the gate is in the opposite direction, the balls willroll along flange 134 on guide 136.

A hydraulically balanced seat is provided for sliding gate 66, the seatcombining with the ball bearing arrangement above-described, so thatfriction on the gate will be at a minimum value. Bell-mouthed retainer138 is formed on the wall of venturi 64 just downstream of gate 66.Guide 140 lits within the retainer and is secured in place bycastellated locking ring 142 which is threaded to the retainer bythreads 144. O-ring seal 14,6 is located between the retainer and theguide. Ring carrier 148 is mounted within guide 14u and is grooved toreceive a plurality of sealing rings 150. Sleeve 152 has a circularsection closely fitting within carrier Bl-S and a rectangular section154 (FIG. 3) immediately adjacent the downstream face of gate 66 in theplane of contact with the gate. The sleeve is welded to the carrier atthe downstream ends of the elements. Bellows 156 is located around aportion of sleeve 152 and is welded to llange 153 on the sleeve and theupstream end of guide 140. Rings G provide a seal between carrier 14Band guide 14d and limit the leakage of fuel into the conduit ldownstream of the gate in the event of failure of bellows 156.

As should be obvious from the construction of the seat, sleeve 1552 andcarrier 143 are free to slide axially of the seat, bellows 156 sealingthe interior of the seat from fluid upstream of the gate. This freedomof axial movement allows for realignment or readjustment of the seat ifthe valve or seat should become worn, or if a foreign substance shouldbecome lodged between the seat and the valve. In either of these events,the seat will move to assure that the friction force between the seatand the valve remains at an essentially constant value determined by thebellows spring load. The effective area of rectangular section 154 isequal to the effective area of bellows 156 with the result that the seatis hydraulically balanced. lt will be observed that the exact locationof the effective area of the bellows is not crucial. The importantconsideration is that the effective area of the bellows is designed tomatch the area of rectangular section 154. Referring to FIGS. 7 and 8,it can be seen that, because of the rectangular nature of section 154,the point of contact between section 154 and gate 66 moves outwardly andoverlaps bellows 156 and flange 158 as the diagonals of section 154 areapproached. Referring to FIG. 8, it can be seen that the exposure offlange 158 to pressurized fluid decreases and is eliminated as thediagonals of section 154 are approached. Also, the final convolution ofbellows 156 is grounded to guide 140 at a point short of the outerdiameter of the convolution so that the pressurized fluid only acts overa portion of the area of the final convolution. These last two factscooperate to produce a hydraulically balanced valve seat which isinsensitive to changes in pressure of the fluid in the valve. Section154 is rectangular rather than circular to keep the required travel forpiston 70 and gate 66 as small as possible. As shown, the travelrequired to fully open gate 66 is substantially less than it would be ifsection 154 Were circular and of the size of the bellows eifective area,and thus, the envelope for the shutoff valve can be kept as small aspossible. The only axial loading on gate 66, aside from that of theupstream fluid pressure, is that of the bellows spring load. The fluidpressure loading is taken by balls which afford little resistance tomotion of the gate. The bellows spring load on the gate is relativelysmall, also affording little resistance to motion of the gate.

It is to be understood that the invention is not limited to the specicembodiment herein illustrated and described, but may be used in otherways without departure from its spirit as defined by the followingclaims.

We claim:

l. In a fluid supply system, a supply conduit, a shutod valve in saidconduit, said valve including a sliding gate mounted in said conduit, asupply of cooling fluid, means automatically circulating the coolingfluid through said conduit when said gate is closed and shutting oif thelow of cooling fluid when said gate is open, and means for providingrelatively friction-free sliding of said gate, said latter meansincluding an antifriction bearing mounting and a hydraulically balancedseat for said gate.

2. In a iluid supply system, a supply conduit, a shutoff valve in saidconduit, said valve including a sliding gate mounted in said conduit,pressure responsive means for opening and closing said gate, a supply ofcooling iluid, means automatically circulating the cooling fluid throughsaid conduit when said gate is closed and shutting off the flow ofcooling fluid when said gate is open, and means for providing relativelyfriction-free sliding of said gate, said latter means including anantifriction bearing mounting and a hydraulically balanced seat for saidgate.

3. In a fluid supply system, a supply conduit, a shutoff valve in saidconduit, said valve including a sliding gate mounted in said conduit,pressure responsive means for opening and closing said gate, means foradmitting a cooling fluid to said valve, check valve means in saidadsaid gate to provide relatively friction-free sliding of said gate.

valve in said conduit, said valve including a sliding gate controllingflow therethrough, a continuous ball bearing track arrangement forguiding sliding movement of said gate, said arrangement including ballsin grooves in said gate, and a hydraulically balanced seat for saidgate.

5. In a fluid supply system, a supply conduit, a shutoff valve in saidconduit, said valve including a sliding gate controlling owtherethrough, a ball bearing mounting arrangement for said gate, and ahydraulically balanced seat for said gate, said seat including a movablesleeve and bellows means connecting said sleeve to a fixed retainer,said sleeve contacting said gate to form said seat and having aneffective area in the plane of contact equal to the effective area ofsaid bellows means.

6. In a iuid supply system, a supply conduit, a shuto valve in saidconduit, said valve including a sliding gate controlling ilowtherethrough, a ball bearing mounting arrangement for said gate, and ahydraulically balanced seat for said gate, said seat including a movablesleeve and bellows means connecting said sleeve to a ixed retainer, oneend of said sleeve contacting said gate and being of rectangular sectionin the plane of contact, the effective area of said rectangular sectionbeing equal to the effective area of said bellows.

7. In a fluid supply system, a supply conduit, a shutoff valve in saidconduit, said valve including a'venturi defining the flow conduitthrough the valve and a sliding gate mounted at the throat of theventuri, antifriction mounting means for said gate, and a hydraulicallybalanced seat for said gate, said seat including a movable sleeveconnected by bellows means to a xed retainer, one end of said sleevecontacting said gate vand being of rectangular section at the area ofContact, the eliective area of said rectangular section being equal tothe effective area of said bellows.

4. In a fluid supply system, a supply conduit, a shutol 8. In alluidsupply system, a'supply conduit,a shutoi valve in said conduit,saidvalve including a venturi dening the flow conduit through the valveand a sliding gate mounted at the throat of the venturi, piston meansvoperatively connected with said gate, means for loading said piston inopposite directions to open and close said gate,

means for admitting a cooling fluid to said valve, check valve meanscontrolling the circulation of said cooling iiuid through said valve, aball bearing mounting for guiding said gate inopening and closingmotion, alternate balls in said arrangement being of different diameter,and a seatl for said gate including a slideable sleeve connected by abellows to a fixed retainer, one end of said sleeve contacting said gateand being of rectangular section in the plane'of contact, the effectivearea of said rectangular section being equal to the effective area ofsaid bellows to hydraulically balance said seat.

9. A fluid supply system as in claim 1 wherein the means for circulatingand shutting off the cooling flow includes means responsive to thepressure in said conduit.

References Cited in the tile of this patent UNITED STATES PATENTS327,117 Strebel Sept. 29, 1885 701,944 Saltar .Tune 10, 1902 898,945Weibel-Mulish Sept. 15, 1908 935,769 Turner Oct. 5, 1909 1,289,673Coggin Dec. 26, 1916 1,439,720 Yarnall Dec. 26, 1922 1,631,481 GfellerJune 7, 1927 1,823,394 Geiger Sept. 15, 1931 2,063,655 Barner Dec. 8,1936 2,221,724 Saitord Nov. 12, 1940 2,331,465 Fox Oct. 12, 19432,548,128 Snyder Apr. 10, 1951 2,569,857 Jaegle Oct. 2, 1951 2,796,230Grove June 18, 1957 2,899,798 Broders Aug. 18, 1959

1. IN A FLUID SUPPLY SYSTEM, A SUPPLY CONDUIT, A SHUTOFF VALVE IN SAIDCONDUIT, SAID VALVE INCLUDING A SLIDING GATE MOUNTED IN SAID CONDUIT, ASUPPLY OF COOLING FLUID, MEANS AUTOMATICALLY CIRCULATING THE COOLINGFLUID THROUGH SAID CONDUIT WHEN SAID GATE IS CLOSED AND SHUTTING OFF THE